code: def test_no_fill_na(df_daily):
      """Test no ``series_na_fill_func``."""
      df_train = df_daily["df_train"]
  
      model = LagBasedEstimator(series_na_fill_func=None)
      model.fit(df_train)
      # Checks ``model.df``.
      # It should include the past 1 week NA data due to no NA fill function.
      df_expanded = pd.concat(
          [
              pd.DataFrame(
                  {
                      "ts": pd.date_range(
                          start=df_train["ts"].iloc[0]
                          - timedelta(weeks=1),
                          periods=7,
                          freq="D",
                      ),
                      "y": np.nan,
                  }
              ),
              df_train,
          ],
          axis=0,
      ).reset_index(drop=True)
      assert model.df.equals(df_expanded)
  
      # Checks prediction within training.
      df_fit = model.predict(df_train)
      # The value column should be the same as the input.
      assert df_fit["y"].equals(df_train["y"].astype(float))
      # The first week's fitted values are all NANs due to no NA fill function.
      print(df_fit[PREDICTED_COL].iloc[:7].reset_index(drop=True))
      print(pd.Series({"y": [np.nan] * 7}))
      assert (
          df_fit[PREDICTED_COL]
          .iloc[:7]
          .reset_index(drop=True)
          .equals(pd.DataFrame({"y": [np.nan] * 7})["y"])
      )
      assert list(df_fit.columns) == ["ts", "y", PREDICTED_COL]
  
imports: from datetime import timedelta
  import numpy
  import pandas
  import pytest
  from dateutil.relativedelta import relativedelta
  from testfixtures import LogCapture
  from greykite.common.constants import ERR_STD_COL
  from greykite.common.constants import LOGGER_NAME
  from greykite.common.constants import PREDICTED_COL
  from greykite.common.constants import PREDICTED_LOWER_COL
  from greykite.common.constants import PREDICTED_UPPER_COL
  from greykite.sklearn.estimator.lag_based_estimator import LagBasedEstimator
label_desc: Use image node_id 10 for calling a global function with example usage: test_no_fill_na(df_daily) without return types